The invention to which this application relates is a fixture in the form of a mechanical connection device and particularly, but not exclusively, to a fixture for joining concrete reinforcing steel bars, for joining any other surface profiled bars or creating an anchor on a single profiled bar.
Concrete reinforcing steel bats are used, as the name suggests for reinforcing concrete structures. The bars can be provided in different sizes and have different forms of rib patterns on their outer surfaces, to provide a mechanical interface between the bar and the concrete which surrounds the bar in use. The steel bars typically have to be mechanically connected together in forming the structure but conventional methods can compromise the fatigue performance and strength of the bars, which in turn, compromises the integrity of the final structure.
The technical requirements of the reinforcing bars generally relate to providing optimal tensile/compressive capability, strain performance and fatigue life. Conventionally, specialised equipment is employed to achieve these requirements, either at the point of installation or at a location where an additional process his to be carried out. One such example of a connector for connecting two bars together and requiring additional machinery is disclosed in U.S. Pat. No. 5,967,691. The ends of the bars in this connector assembly are required to have different outer surface formations to the remainder surface of the bars, thereby allowing shell elements to placed around the bar ends to bridge and connect the bars together. These outer surface formations are required to be machined or welded on. However, deformation of the bar is likely to compromise the fatigue performance of the bar. In addition, the requirement of additional equipment incurs expense through additional handling and the expense of the equipment itself. Furthermore, transport of equipment to the location of construction is often problematic, particularly in less developed countries where transport systems are more primitive. There is also the additional problem in that the skill level required to correctly carry out these specialised operations is not always readily available at the site where the process is to be carried out.
A further type of connector assembly is disclosed in GB2255385, wherein the assembly comprises a set of wedge shaped claws for location at each end of the bars being connected. Two externally threaded inner bushings are located over the claws and are joined to an internally threaded outer bushing, Problems associated with this type of connector are that some of the components require to be screwed together during assembly. As the bars are typically heavy and embedded in concrete, they are often not capable of being rotated. In addition, embedding of the assembly components onto the bars and with each other typically does not occur until application of the service load of the structure (load of the assembled structure on the bars in use). As a result, slipping of the components occurs on application of the service load, thereby resulting in cracking and/or damage to the structure.
It is therefore an aim of the present invention to provide a fixture in the form of a mechanical connection device for connecting together lengths of profiled material, such as concrete reinforcing steel (rebar), the fixture overcoming the abovementioned problems and being capable of use with material of different sizes and different outer surface profiles.
It is a further aim of the present invention to provide a fixture which can be used in accordance with the relevant international requirements, such as tensile/compressive capability, strain performance and fatigue life, without the need for any specialised equipment and by the most cost-effective means.
According to a first aspect of the present invention there is provided a fixture for connecting two or more concrete reinforcing members together in end to end relationship, said two or more members having outer profiled surfaces, said fixture including sets of inner segments, intermediate segments and an outer sleeve and characterised in that each set of inner segments have formations co engage with the outer profiled surfaces of each end of the members being connected, said inner segment formations being of complementary dimensions to the outer profiled surfaces of the members for location therewith, the intermediate segments having formations on an inner surface thereof complementary to formations on the outer surface of the inner segments to provide mechanical interlock therebetween, and an outer sleeve positionable around the sets of inner segments and intermediate segments to maintain the same in position.
Preferably the set of inner segments include a pair of segments for location around each of the two members, being of sufficient length to generate sufficient rib shear area.
Further preferably the set of intermediate segments includes a pair of segments for location around said inner segments and said two or more members.
Preferably the inner segments have the formations on an inner surface, and are of complementary dimensions to the profiled surface of the members. The inner segments can also be provided with a profiled outer surface fur engagement with complementary formations on the inner surface of the intermediate segments and these surfaces typically include fine pitch thread.
Preferably a semi-compressible fluid or coating is provided between the members and the inner segments to reduce clearance therebetween. In one embodiment this fluid is an extrudable coating. The coating intimately interfaces with the members to be joined in order to avoid any slip, and transfer any load within the members to their mating components.
In one embodiment the two or more members are elongate bars provided with a plurality of ribs on their outer surfaces.
Preferably the inner segments can be held in place by securing means in the form of a spring clip, rubber band, tying wise and/or the like, which is located in a recess portion on the outer surface of the segments.
In a further embodiment of the present invention an outer sleeve is provided for locating around the intermediate segments to maintain the components in position. Preferably in this embodiment the intermediate segment is tapered and the outer sleeve has a complementary taper to provide a frictional fit between the same The taper is typically between 0-3 degrees.
In an alternative embodiment no outer sleeve is provided and the intermediate segments are the outermost component of the assembly. In this embodiment fastening means are provided on the intermediate segments to secure the assembly together. Preferably these fastening means are recessed or flush with the outer surface of the intermediate segments.
Typically, the internally coned outer sleeve is driven over the intermediate segments by manual force such as by a hammer and generates a radial compressive force. This force embeds the inner segments onto the members and into the intermediate segments taking up any clearances caused by manufacturing tolerances of all components thereby minimising slip.
In a preferred embodiment the outer sleeve has an indication device, which will inform the installer when sufficient hammer blows have been applied.
The mechanical splice in accordance with the invention meets the needs of the commercial market, and has the following design features:
An intimate mechanical interlock with each of the members to be joined which has sufficient cross-sectional area in axial shear to be able to withstand the full tensile/compressive strength of the members without movement or slip, including the situation where load reversal occurs.
A large enough cross-sectional area at the location of the highest tensile stress to be able to withstand the full tensile capability of the members.
The mechanical connector does not adversely compromise the fatigue performance of the members.
In a second aspect of the present invention there is provided a fixture for connecting at least one concrete reinforcing member to an object, said at least one member having outer profiled surfaces, said fixture including sets of inner segments, intermediate segments and an outer sleeve and chatacterised in that each set of inner segments have formations to engage with the outer profiled surfaces of each end of the members being connected, said inner segment formations being of complementary dimensions to the outer profiled surfaces of the members for location therewith, the intermediate segments having formations on an inner surface thereof complementary to formations on the outer surface of the inner segments to provide mechanical interlock therebetween, and an outer sleeve positionable around the sets of inner segments and intermediate segments to maintain the same in position.
In a further aspect of the invention there is provided a fixture for connecting two or more elongate concrete reinforcing members in end to end relationship, said members provided with ribs on an external surface thereof, said fixture including sets of inner segments, intermediate segments and an outer sleeve and characterised in that each set of inner segments have formations to engage with the ribs at each end of the members being connected, said inner segment formations being of complementary dimensions to the ribs on the members for location therewith, the intermediate segments positionable around the inner segments and having formations on an inner surface thereof complementary to formations on the outer surface of the inner segments to provide mechanical interlock therebetween to maintain the same in position, and an outer sleeve which passes over the intermediate segments and mechanically engages the segments and members in the end to end relationship.
In a yet further aspect of the present invention there is provided a method of forming the fixture components and assembling the fixture components in use.